Former White House Chief of Staff Bill Daley announced Monday night he is ending his bid for governor of Illinois, essentially clearing the field for incumbent Pat Quinn to win re-election.

Daley's surprise announcement comes just four months after he declared he was the best candidate to unseat Quinn in the 2014 gubernatorial race.

In an interview with the Chicago Tribune, Daley, the son of the late Chicago Mayor Richard J. Daley, said running for the Governor's Mansion was always a dream of his, but believes the task is too tall.

“One of the things I always thought in my career that I wanted to do, I thought I would be able to have that opportunity, I hoped, would be to run for office. And even though you’re around it for a long time, you really don’t get a sense of the enormity of it until you get into it,” Daley told the Tribune.

The decision by Daley leaves the Democratic primary field Quinn's to lose as he looks to shore up the party's nomination. However, there is still time for a Democrat to step up and challenge Quinn before the December filing date. Daley did say he believes another challenger should step up, adding Quinn isn't the best man for the job.

“There’s no doubt in my mind that Pat Quinn will not be the next governor of Illinois,” said Daley. “This governor is not that strong that somebody should fear running against him," Daley told the Tribune.

Quinn's approval ratings are among the lowest in the country, and Illinois Republicans believe they have a strong chance of winning in 2014. Currently, there are four candidates: state Treasurer Dan Rutherford, businessman Bruce Rauner and state Sens. Bill Brady and Kirk Dillard.

Daley told the Tribune Monday night he plans to return to the private sector — however, he will not seek public office.

“Life goes on,” he said. “Tomorrow we’ve all got to pay our bills and, hopefully, we put our feet down on the floor and get up and life goes on — and life will go on not only for me, but for everybody else in this state.”